Host for use with dual interface card with backward and forward compatibility

ABSTRACT

A host device includes a slot configured to receive a first type of memory card having an indentation and a mechanical structure. The mechanical structure includes a pivot structure and a lever arm. The lever arm is configured to pivot on the pivot structure and a portion of the lever arm is configured to at least partially fit into the indentation to distinguish the first type of memory card from a second type of memory card.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.12/717,072 filed Mar. 3, 2010, which is a continuation of U.S. patentapplication Ser. No. 12/676,339 filed Mar. 3, 2010, which claims thebenefit from International Application No. PCT/IB2009/006841, filed Sep.15, 2009, and from U.S. Provisional Application No. 61/234,133, filedAug. 14, 2009. The contents of these applications are incorporated byreference herein in their entirety.

FIELD OF THE DISCLOSURE

This invention relates generally to the use and structure of removableelectronic circuit cards having different mechanical and/or electricalinterfaces, particularly those including mass re-programmablenon-volatile integrated circuit memory.

BACKGROUND

Electronic circuit cards, including non-volatile memory cards, have beencommercially implemented according to a number of well-known standards.Memory cards are used with personal computers, cellular telephones,personal digital assistants (PDAs), digital still cameras, digital moviecameras, portable audio players and other host electronic devices forthe storage of large amounts of data. Such cards usually contain are-programmable non-volatile semiconductor memory cell array along witha controller that controls operation of the memory cell array andinterfaces with a host to which the card connected. Several of the sametype of card may be interchanged in a host card slot designed to acceptthat type of card. However, the development of the many electronic cardstandards has created different types of cards that are incompatiblewith each other in various degrees. A card made according to onestandard is usually not useable with a host designed to operate with acard of another standard.

A number of standards exist for memory cards, which continue to evolveas new standards are introduced. For example, one generation of memorycards may introduce a higher speed bus than a preceding generation. Forpracticality in the market, it is desirable to optimize the userexperience with minimal frustration along with an effort to minimize thehost and card manufacturer's risk by keeping backward compatibility witholder protocols at various levels.

SUMMARY

In view of the foregoing, a number of embodiments of system and methodare illustrated and described in this document to exemplify possibleimplementations. One embodiment is that of a non-volatile memory cardthat is operable according to a first protocol and a second protocol andis removably connectable to a host through a slot formed in the host forconnection of the memory card to it. The memory card has a first set ofcontacts for physically and operatively coupling between the memory cardand the host according to the first protocol. The memory card has also asecond set of contacts for physically and operatively coupling betweenthe memory card and the host according to the second protocol. The firstand second sets of contacts differ by at least one of the contact. Thememory card also includes an indentation along a first edge that isorthogonal to a second edge of the memory card. When the second edge ofthe memory is inserted into the slot of a host, when the memory card isinserted into this slot, the host can identify this memory card as onewhich is operable according to the first protocol and distinguish itfrom a second type memory card of a similar form factor except for theindentation and that is not operable according to the first protocol.

A digital appliance is presented that includes a slot structure havingan opening, possibly rectangular, to allow a first type memory cardhaving a first set of contacts to be removably connected by insertioninto the slot structure to operate with the digital appliance accordingto a first protocol. The slot structure having formed within it amechanical structure that can distinguish the first type memory cardfrom a second type memory card, where the second type memory card has asecond set of contacts, where the first and second sets of contactsdiffer by at least one of the contacts, and the second type memory cardbeing operable according to a second protocol not supported by thedigital appliance and not being operable according to the firstprotocol. The first and second type memory cards have a similar formfactor except for an indentation along a first edge of the first typememory card, the first edge being a different edge than the one insertedinto the digital appliance when the memory card is inserted into theslot for connection thereto, whereby the mechanical structure preventsthe connection of the second type memory based on the lack of theindentation.

Various aspects, advantages, features and embodiments of the presentinvention are included in the following description of exemplaryexamples thereof, which description should be taken in conjunction withthe accompanying drawings. To the extent of any inconsistency orconflict in the definition or use of terms between any of theincorporated publications, documents or things and the presentapplication, those of the present application shall prevail.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B show two examples of an embodiment of a memory cardhaving two sets of electrical contacts that conform with differentindustry specifications;

FIG. 2 is an electronic block diagram of the memory system within thecard of FIGS. 1A and 1B;

FIG. 3 illustrates use of the card of FIGS. 1A, 1B and 2 with differenttypes of electronic equipment;

FIGS. 4A and 4B show an exemplary mechanical structure eliminatinginsertion of a card for one standard to a host of another standard;

FIG. 5 illustrates a card with for a dual interface and a card with justthe legacy interface inserted to a legacy host;

FIG. 6 shows an example of a dual interface with a dual insertion pathcard;

FIG. 7 is another exemplary mechanical structure eliminating theinsertion of one card type to second type host;

FIG. 8 shows dual interface card (with dual insertion paths) insertedinto a legacy host.

DETAILED DESCRIPTION

As noted in the Background, a number of standards exits for memorycards, which continue to evolve as new standards are introduced. Forexample, one generation of memory cards may introduce a higher speed busthan a preceding generation. Such newer generation cards could bedefined by an infrastructure based on a new generation of hardware andnew interface pinout. For practicality in the market, there is amotivation is to optimize the user experience with minimal frustrationalong with effort to minimize the host and card manufacturer's risk.This can be done by keeping backward compatibility with older protocolsat various levels. Assuming that this backward compatibility is notmandatory for all sides (host and card) at all times there is a need tohandle cases of non compatible devices matches. Further, it may happenthat initially new host will support both interfaces and after sometransition period they will remove the support of legacy protocolsupport. Although more generally applicable, the various embodimentshere provide user friendly solutions that protect both card and hostfrom any “illegal” combination, such as connecting an old card to a hostsupporting only new card. The techniques given here also provide asimple method for a user to decide whether to use the old interface orthe new interface method.

Such evolution has occurred in the past and been dealt with in variousways. One way is for cards and hosts that continue to support the legacyprotocol and new protocols; but this often limits optimization of thecost aspect advantages and moving forward with advanced technology ofthe new protocol. Another approach is using an adaptor as a mediatorbetween one structure and another, such as, for example, a micro-SD™ toSD™ adaptor. (Adaptors are discussed in U.S. Pat. No. 5,887,145, forexample, which is hereby incorporated herein by this reference in itsentirety.) Yet another approach is marking the new card with a visiblesign that indicates the user the card's compatibility or incompatibilityto proper hosts. The problem is that users are often confused by thevarious card types and it may happen that user will try to insert an oldcard to new hosts (especially if the card's slot and the new/old card'sform factors look mechanically the similar). There are solutions in themarket that support cases in which new cards cannot be inserted to oldhosts but old cards can be inserted to new protocol hosts (for example,the MMC—SD case)—a solutions usually implemented by different mechanicaldimensions. The present case being developed in the following is mainlyconcerned with multi interface hosts and/or cards and a need toeliminate or allow cards to be inserted to hosts depends on the use-case(i.e., legacy card should not be inserted to new host that supports onlythe newer mode of operation). For example, the techniques presented herecould be adopted by standards such as an UFS (Universal Flash Standard)or UHS-II (Ultra-High-Speed 2.sup.nd generation) standards as defined bythe JEDEC standard body or SD Association™, respectively, if and asthese are combined with legacy SD™ standard or an SD backward compatibleform factor card.

More specifically, the methods provided here can be used separately orin combination to allow a better user experience in case of new memorycard specification introduction to a market that widely uses a legacycard. For purposes of discussion, the following will mainly use theexample where the legacy card is of the micro-SD (or “.mu.SD” in theFigures and Table 1) type and the new interface card (“NEW”) card, suchas of the UFS or UHS-II standards mentioned above, with a similar formfactor. In order to support both new and old protocols at least for sometransition period, the following cards options are possible:

1) Legacy card (micro-SD);

2) Dual interface card (micro-SD-NEW);

3) New interface card (NEW);

and the following host options are possible:

1) Supports only legacy interface (SD)

2) Supports both interfaces (NEW and SD)

3) Supports only new interface (NEW).

Table 1 shows the various card-host matchers for card insertion attemptsby users and the functional support:

TABLE 1 Possible card - host matches Host Card Legacy μSD + NEW NEW μSD(legacy) ✓ ✓ X1 μSD − NEW ✓ ✓ ✓ NEW card X2 ✓ ✓

It should be noted that this discussion also applies to cases where the“NEW” protocol is just an updated or evolved version (e.g., an evolvingversion of SD, such as UHS-II) of an earlier protocol; for example,additional contacts may be added to an existing standard to increase thedata transfer rate and the protocol updated accordingly.

In order to allow the best user experience, the desirable situationwould be that all cards will work in all hosts (the situation ofmicro-SD-NEW card and SD+NEW hosts), but as a practical matter (such ascost of hosts and or cards) that typically would not happen after some,possibly long, transition period. Therefore, the cases of non-functionalmatches (those marked by “Xn” in the table) need to be taken care andallow optimal user experience for users.

To resolve the above mentioned issue, the embodiments below present afew mechanical design methods that will eliminate from users the abilityto get into the above “X” situations of Table 1. In order to preventusers from inserting a legacy card into a new host that does not supportlegacy cards (case X1 in table 1) a mechanical invention is proposed.The general idea is to use a mechanical structure that allows the new ordual interface card to be differentiated from legacy card, but stayingwithin the legacy (micro-SD in the example) form factor physical margins(allowing it to be inserted to legacy hosts) and, on the host side, tohave an automatic mechanism that will distinguish between old card andnew or dual interface cards and allowing only the dual interface or newcards to be fully inserted.

In order to provide a portable non-volatile memory that is connectabledirectly with various types of host devices that include a slot orreceptacle having various physical and electronic signal protocol andformat characteristics, two or more external sets of electrical contactsare provided on a memory card system that conform to different standardsand specifications. The internal memory of the card system, mostcommonly flash memory, is operable through any of the sets of contactsalone with the appropriate signal protocol. The standards that areimplemented are preferably those that will allow the system to be useddirectly with a wide variety of host devices.

The example memory card systems described herein utilize one set ofcontacts and a signal protocol from one published memory card standard,such as that for the micro-SD card, and the other set of contacts and asignal protocol according another standard. Although more widelyapplicable, to provide a concrete example for discussion, in thefollowing one of the standards will taken as a micro-SD (“.mu.SD”) cardand treated as a legacy product. The other standard will be taken as acard of a similar form factor, but with a different set of contacts,operating protocol, or both. The two set of contacts may be distinct orshare some of the contacts. In some cases, one set may be entirely asubset of the other. The types of hosts or “digital appliances” mayinclude examples such cell phones, PDAs, MP-3 players, cameras, personalcomputers, notebook computers and the like. Additionally, althoughdiscussed here for two different protocols, the discussion can beextended to other numbers of multiple protocols.

FIGS. 1A and 1B show two examples of a dual interface card. In bothcases the form of the memory card system is based on standard unitarymemory card with a second set of contacts added. Both the card of thenew standard and the legacy standard have similar form factors, in thatthe form factor physical margins are the same (the micro-SD card in thisexample), but differ slightly, as described below.

Referring to FIG. 1A, this shows an exemplary embodiment of a memorycard 101 having a physical form factor with margins the same as onestandard, in this case the micro-SD card, but with an additionalindentation 135 formed into its side. According to the micro-SD MemoryCard Specifications, eight electrical contacts 111-118 are provided,along with an additional eight contacts 121-128. In the new standard,all of both sets of contacts or some subset could be used for operationin the according to the corresponding protocol. As will be described,the indentation 135 can be used by a host to distinguish a dualinterface card, or a card with just the new interface, from a legacycard. In a an arrangement such as card 101, where the card is insertedinto the host along the same edge and both interfaces share at leastsome of the contacts, such a mechanism can be particularly useful for ahost to engage the card with the correct protocol.

FIG. 1B shows another exemplary embodiment for a dual interface card. Inthis embodiment, the card 101′ again has a physical form factor withmargins the same as that of a micro-SD card and contacts 111-118 of themicro-SD standard. The additional set of contacts 141-150 are for useaccording to a different protocol. FIG. 1B presents an example where,for engagement according to the additional protocol, the card isinserted in a host by its right side and the corresponding indentation135′ along the bottom edge. In both of FIGS. 1A and 1B, the side withthe indentation and the side inserted into the host when the indentationis used are shown as orthogonal, although other angles may be used.

The electronic block diagram of FIG. 2 shows generally one possibleexample of the electronic system within the structure of card 101 or101′ of FIGS. 1A and 1B. Flash memory 201 can be accessed from themicro-SD card contacts 111-118 through a controller circuit 203. Thesecond set of contacts (111-118 or 141-150) is connected to thecontroller 203 through an interface circuit 205. Alternatively, a singlecontroller can be used in place of the circuits 203 and 205 to provideboth signal protocols, or an additional separate interface could also beincluded for the contacts 111-118. If one or more additional sets ofcontacts are provided, provision is made to interface the additionalset(s) of contacts with the signal protocols of the additionalstandard(s).

Using the two interfaces, the resulting memory system of FIGS. 1A, 1Band 2 is useable with a wide variety of types of host devices. This isillustrated in FIG. 3. The hosts and cards may be of any of the typesdescribed above with respect to Table 1. The card, such as the dualinterface card of 101 or 101′ or a single interface card would insertedinto a memory card slot of a hosting digital appliance such as PDA 301or of a notebook computer 303. By use of the indentation 135, 135′ andsort of structure within the host described below with respect to FIG. 4or 7, the undesired cases of Table 1 can be avoided.

More detail on card structures and hosts, including a number of aspectsthat can be incorporated here, is presented in the U.S. Pat. Nos.7,305,535 and 7,364,090, which are hereby incorporated herein by thisreference in their entirety. Again, it should be noted that although thepresent discussion is based on the example of a device with a formfactor based on the micro-SD standard, and that this is treated as alegacy device, this in only one example and the techniques presentedhere are more generally applicable. For example, other embodiments couldbe based on a (non-micro) SD card as the example of a “legacy” standardand a card of similar form factor, but with, say, extra contacts addedas the other standard.

FIG. 4A shows one example of a such a solution on the host side fordealing with the “X1” case of Table 1, by introducing a mechanicalstructure eliminating the insertion and engagement of (in this example)a legacy micro-SD card into a host which supports the NEW, but not thelegacy, standard. FIG. 4A shows the inside of the slot structure 420 ofhost that only supports the NEW interface/protocol. The mechanicalstructure 421 within the slot allows a conforming to the NEW standard,whether a dual interface card or just single NEW interface, to engage,while not allowing the legacy card to engage. The opening of the slotitself can have an opening of the typical rectangular, or roughlyrectangular, shape common to such slots, although other arrangements maybe used. At left, a micro-SD-NEW card 101 with dual interface support(based on a card in which a second row was added for the NEW interfacesupport). The lower end (as oriented in the figure) of mechanicstructure 421 moves into the indentation of the card 101. The structure421 is arranged in the manner of a see-saw, so that as the lower endmoves into the indentation on the card 101, the lever arm swings on themedial pivot point so the upper end of the structure 421 moves out ofthe way, allowing the card to engage to the host. The given small changein the form-factor allows the mechanical mechanism 421 in NEW hosts torecognize the card as supporting the NEW interface/protocol. As shown onthe right side of FIG. 4A, for a legacy card 401, as it lacks theindentation, the mechanical structure 421 prevents the card 401 fromengaging in the slot 420. FIG. 4B shows the slot structure 420 of thehost without the card. In this exemplary embodiment, the mechanicalmechanism 421 is shown to be made up of a first element 423 that wouldfit into the indentation of a card such as 101. The element 425 wouldthen either block the card from engaging, if the indentation is absent,or move out of the way to allow the card to engage as the connecting rodor beam 429 pivots on 427. These various elements of the structure 421can be formed of plastic, metal, or other materials and, althoughseparately number for explanatory purposes, may be formed as a singlepiece or multiple pieces that are then joined. For example, all of 423,525 and 429 could be formed of a single piece of plastic or 425 and 423may be attached to a 429 of a more rigid metal.

Both the change to the card's form factor and the mechanical structurefor the host side are readily implemented and do not affect theinsertion of a dual interface card into a legacy (i.e., micro-SD) host.As shown in FIG. 5, the slot 520 of such host will accept a dualinterface card 101 (at left) the same as a legacy micro-SD card 410 (atright).

FIG. 6 shows the embodiment for a dual interface card 101′ with dualinsertion path of FIG. 1A, but with differing insertion paths indicated.The contacts 111-118 are those of the one interface (here, the “legacy”micro-SD interface) and the contacts 141-150 that of the other. (Notethat, as before, the NEW interface pinout and location is just anexample.) FIG. 6 illustrates using the same micro-SD physical formfactor that includes both legacy and new interfaces, but with twodifferent insertion paths for the two protocols. Using the “narrow” cardside for the micro-SD insertion path (as defined for legacy cards) andthe ‘wide’ card side for the new NEW interface usage. The indentation135′ is again along the side perpendicular to the edge inserted into theslot for engagement. Such structure allows usage of the same micro-SDcard in all 3 types of hosts of Table 1.

The NEW hosts can have a wider slot, which would provide an additional,visible, indication for users not to insert old cards to such slots. Inaddition, in cases that both host and card supports both protocols (newand old), it provides the user the capability to choose the protocolmethod to be used by the direction the card is inserted. FIG. 7 shows anexample of the same, above mentioned, mechanical solution as used forthis type of dual-insertion-path cards.

Referring to FIG. 7, this illustrates another embodiment for eliminatingthe insertion and engagement of a micro-SD card 410 into the slot 720 ofa NEW host by its “wide” side. As shown at the left, when a dualinterface card 101′ (or single interface NEW card) is inserted, one endof the mechanical structure 721′ moves into the indentation 135, so thatthe other end moves to the side. The card 110′ can then engage to withthe host using the contacts 141-150. As shown on the right side, alegacy card 410 lacking the indentation 135 and the mechanical structure721 will prevent the card's engagement. Under this arrangement, hostsintended to support both protocols (micro-SD and NEW) will need to havethe capability to accept card in both insertion paths (a wide for NEWmode and a narrow for SD mode). The given micro-SD-NEW design is stillbackward compatible to legacy micro-SD hosts and will be inserted andfunction the same as regular micro-SD card This is shown in FIG. 8, whenboth a dual interface card 110′ (at left) and a legacy card 410 (atright) can be inserted in the slot 720 of a legacy micro-SD host.

The above techniques are based on mechanical and visualpreventions/alerts to be used for “illegal” card-host matches. Another,complementary approach to handle such incompatibilities can be by usingan electrical detection of card insertions/removal along with attempt toinitialize the card using the relevant protocol (either old or new). Theidea is as follows: Both type of cards (old and new) may be insertedphysically to old/new hosts. Assuming that legacy host is using anelectrical method for card detection (either electrical switch ordedicated pad (with pullup/pulldown resistor as suggested in SD cardspec), the new hosts (including future hosts that intend to support onlythe new interface can use the such electrical methods. (Note that suchan electrical method can be used in combination with the mechanicaltechniques for extra assurance.)

After any card-type insertion the host will detect the insertion throughthe given electrical method. Upon card insertion detection the host willattempt to initialize the card using either one of the protocols—old ornew. In ease of non-matched card-host the host will not be able toinitialize the card. If such case occurs the host will be able to informthe user (through available GUI) that a Non-Compatible card was insertedto the host. In such a way the user will get feedback from the host thatconfirms the card insertion and its non-compatibility. Some detailsrelating to an automatic protocol selection mechanism are described inU.S. Pat. No. 7,360,003, which is hereby incorporated herein by thisreference in is entirety.

As described above, a number of aspects are presented. According to oneof these, a method is presented for providing capability to preventillegal/unsupported match between new/old card type and new/old hostupon the supported functionality. In another aspect, this will alsocover the case in which an old card is not supported by a new host thatdoes not support old cards, but will be supported by new host that doessupport old cards. Other aspects include implementing this using amechanical, automatic mechanism. In one set of embodiments, a methodthat is supported by the insertion-path the cards (new/old) are inserted(through wide or narrow edge) each path dedicated for the different typeof protocol, a method that also provides for a user to select betweennew or old protocol by using a different insertion path to the samecard.

These techniques allow a good compromise between market needs for lowcost memory card transition to new standards and the user's experienceof compatibility needs with legacy card standard. The current inventionprotect from any illegal/unsupported insertion and also provides amethod that allows the user to select the active interface by the way heinserts the card.

Although the foregoing aspects have been described in the context ofseveral exemplary embodiments and variations thereof, it will beunderstood that the appended claims are not limited thereby and theclaimed invention is entitled to protection within the full scope of theappended claims.

What is claimed is:
 1. A host device comprising: a slot configured toreceive an edge of a first type of memory card having a side surface, anindentation in the side surface, and contacts configured to be engagedwith the host device in response to insertion of the edge into the slot;a mechanical structure including: a pivot structure, and a lever armconfigured to pivot on the pivot structure, wherein first and secondportions of the lever arm are configured to, in at least one orientationof the lever arm, contact the indentation and the side surface withoutcontacting the edge; and an edge indentation detector configured todistinguish the first type of memory card from a second type of memorycard based at least in part on a position of the lever arm.
 2. The hostdevice of claim 1, wherein: the first and second portions of the leverarm are nonadjacent, and the mechanical structure is configured to allowthe first type of memory card to be engaged within the slot.
 3. The hostdevice of claim 1, wherein: the first and second portions of the leverarm are further configured to contact another side surface and anapproximately orthogonal surface, respectively, of the second type ofmemory card, and the mechanical structure is configured to prevent thesecond type of memory card from being engaged within the slot.
 4. Thehost device of claim 1, wherein: the first type of memory card has afirst set of contacts, the second type of memory card has a second setof contacts, and the first set of contacts and the second set ofcontacts differ by at least one of the contacts.
 5. The host device ofclaim 4, wherein: at least one contact is common to both the first setof contacts and the second set of contacts, and the edge indentationdetector includes the mechanical structure.
 6. The host device of claim4, wherein the first type of memory card and the second type of memorycard have a similar form factor and respective edges except a first edgeof the first type of memory card that includes the indentation.
 7. Thehost device of claim 6, wherein: the first edge is approximatelyorthogonal to a second edge of the first type of memory card, and theslot is dimensioned to receive a memory card of the first type viainsertion of the second edge into the slot.
 8. The host device of claim6, wherein the form factor has physical margins corresponding to asecure digital memory card form factor.
 9. The host device of claim 6,wherein the form factor has physical margins corresponding to a microsecure digital memory card form factor.
 10. The host device of claim 4,wherein the mechanical structure is configured to prevent connection ofa memory card of the second type based on a lack of an indentation in aside surface of the memory card of the second type to engage the leverarm.
 11. A host device comprising: a slot configured to receive an edgeof a memory card, the memory card having multiple surfaces and contactsconfigured to be engaged with the host device in response to insertionof the edge into the slot; and a mechanical structure including: a pivotstructure; and a lever arm configured to pivot on the pivot structureand comprising: a first element configured to, in at least oneorientation of the lever arm, contact an indentation in a first sidesurface of the multiple surfaces; and a second element configured to, inthe at least one orientation of the lever arm, contact the first sidesurface without contacting the edge, the mechanical structure configuredto distinguish the memory card as a first type of memory card or asecond type of memory card based on whether the first element and thesecond element contact the indentation and the first side surface. 12.The host device of claim 11, wherein: the memory card is of the firsttype, the first element and the second element are nonadjacent, and thememory card is engaged within the slot.
 13. The host device of claim 11,wherein: the memory card is of the second type, the first element andthe second element contact the first side surface and an approximatelyorthogonal surface, respectively, and the memory card is prevented frombeing engaged within the slot.
 14. The host device of claim 11, wherein:the first type of memory card has a first set of contacts, the secondtype of memory card has a second set of contacts, and the first set ofcontacts and the second set of contacts differ by at least one of thecontacts.
 15. The host device of claim 14, wherein at least one contactis common to both the first set of contacts and the second set ofcontacts.
 16. The host device of claim 14, wherein the first type ofmemory card and the second type of memory card have a similar formfactor and respective edges except a first edge of the first type ofmemory card that includes the indentation.
 17. The host device of claim16, wherein: the first edge is distinct from a second edge of the firsttype of memory card, and the slot is dimensioned to receive a memorycard of the first type via insertion of the second edge into the slot.18. The host device of claim 16, wherein the form factor has physicalmargins corresponding to a secure digital memory card form factor or amicro secure digital memory card form factor.
 19. The host device ofclaim 11, wherein the mechanical structure is further configured todistinguish the first type of memory card from the second type of memorycard based at least in part on a position of the lever arm.
 20. The hostdevice of claim 11, wherein: the memory card is of the second type, andthe mechanical structure is further configured to prevent connection ofthe memory card based on a lack of an indentation in the first sidesurface to engage the lever arm.
 21. The host device of claim 11,wherein the mechanical structure is further configured to preventconnection of the memory card based on one of the first element and thesecond element contacting a second surface approximately orthogonal tothe first side surface.
 22. An apparatus comprising: means for receivingan edge of a memory card, the memory card having a side surface, anindentation in the side surface, and contacts configured to be engagedin response to insertion of the edge into the means for receiving; meansfor contacting the memory card, the means for contacting including:first means for contacting, the first means configured to, in at leastone orientation of the means for contacting, contact the side surfacewithout contacting the edge; and second means for contacting, the secondmeans configured to, in the at least one orientation of the means forcontacting, contact the indentation; and means for distinguishing thememory card as a first type of memory card or a second type of memorycard based on whether the means for contacting contacts the side surfaceand the indentation in the side surface.
 23. The apparatus of claim 22,wherein: the first means and the second means are nonadjacent, and themeans for distinguishing is configured to distinguish the memory card asthe first type of memory card based on the first means and the secondmeans contacting the side surface and the indentation, respectively, andbased on the memory card being engaged within the means for receiving.